Method and device for controlling the current in a spark plug

Abstract

The present invention relates to a method of controlling the spark current in a spark plug (8), comprising a voltage source (1; 14), an ignition system (2) connected to the voltage source, and a spark plug (8) connected to the ignition system, which ignition system (2) comprises an ignition coil (3) and at least one regulating unit (5, 6) as well as a control unit (4), enabling control of the intensity and / or duration of the spark current, said ignition coil (3) comprising a secondary side (6, 31) arranged to be controlled in order to control the duration of the spark in Arc Discharge Mode. The invention also relates to an ignition device.

Description

TECHNICAL FIELD[0001]The present invention relates to a method of controlling the spark current in a spark plug, which spark plug is part of a ignition system, the method providing the possibility to control the intensity as well as the duration of the spark current, and thereby also the energy released by the spark. The invention also relates to a device for accomplishment of such control.PRIOR ART[0002]Many of the internal combustion engines of today make use of spark plugs to ignite a mixture of fuel and air. This takes place for example in the Otto engine, in which a premixed mixture of fuel and air is ignited. Spark plugs are also used in direct injection engines, in which fuel and air is mixed directly in the cylinder. Common fuels of today are different types of hydrocarbon compounds, such as petrol, alcohols and various gases such as natural gas and biogas. In the future, hydrogen gas may also be used.[0003]The function of the spark plug is mainly at a given point of time to...

AI Technical Summary

Benefits of technology

"The present invention provides a simple and cost-efficient method to create an ignition system with controllable spark current and duration. This is achieved by using a low control voltage, which is easier to achieve than a higher voltage. The invention allows for an intense spark during a predetermined burning time, which is especially useful for igniting hard-to-ignite fuel mixtures. The spark current and duration can be varied independently of each other, and the control circuit can be connected in a way that minimizes the coupling between the voltage source and the primary side of the ignition coil. This method is especially useful for using the spark plug as an ion current sensor, where it is important to limit the duration of the spark and the time of coil ringing to the initial phase of combustion."

Problems solved by technology

All methods mentioned above disclose the use of a high-voltage source in order to affect the spark current, which is a drawback from the point of view that a high voltage is relatively hard to achieve compared to a lower voltage.

Furthermore, non of the inventions discloses a method of achieving a spark for which it is easy to control the current intensity and duration in Arc Discharge Mode.

Accordingly, no real good method exists today for controlling the spark current in an ignition device, such as a spark plug in a combustion chamber.

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